Release Notes for Safari Technology Preview 166

Safari Technology Preview Release 166 is now available for download for macOS Monterey 12.3 or later and macOS Ventura. If you already have Safari Technology Preview installed, you can update it in the Software Update pane of System Preferences on macOS Monterey, or System Settings under General → Software Update on macOS Ventura.

This release includes WebKit changes between: 260849@main…261247@main.

Web Inspector

  • Added input fields for editing variation axes values in Fonts sidebar panel (261162@main)



  • Implemented RegExp v flag with set notation and properties of strings (261188@main)
  • Enabled new WASM baseline JIT (BBQ) for increased performance (261153@main)
  • Inlined Proxy [[Set]] trap in DFG / FTL (261058@main)
  • Made C++ to JS calls faster (260858@main)


  • Enabled the popover attribute (261193@main)
  • Implemented [popover=auto] and light dismiss behavior (261093@main)


  • Fixed picture-in-picture video snapping to incorrect size (261383@main)


  • Changed to only fire durationchange after parsing the media buffer (261029@main)


  • Added support for preconnect via HTTP early hints (261079@main)
  • Added Cancel, Unknown, and Clear keycodes (261008@main)
  • Added selection API that works across shadow boundaries (261021@main)
  • Added support for largeBlob extension for the local authenticator (260958@main)
  • Adjusted text input scrollWidth and scrollHeight to include padding and any whitespace added by decorations (261121@main)
  • Fixed translation for shadow DOM content (261096@main)
  • Fixed translation to treat a floating list item as its own paragraph (261114@main)
  • Fixed Speech Recognition API terminating after one utterance or a short time (260886@main)
  • Fixed window.onload getting repeatedly re-executed when changing the URL fragment during onload (260860@main)
  • Improved support for prioritized HTTPS navigations (261022@main)
  • Stripped tab and newline from Location, URL, <a>, and <area>‘s protocol setter (261017@main)


  • Fixed input[type=date] individual fields getting announced as “group” (261123@main)
  • Fixed the wrong role displayed for input in Web Inspector (260868@main)